/*
 * This file is part of the OregonCore Project. See AUTHORS file for Copyright information
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include "PetAI.h"
#include "Errors.h"
#include "Pet.h"
#include "Player.h"
#include "Spell.h"
#include "ObjectAccessor.h"
#include "SpellMgr.h"
#include "Creature.h"

int PetAI::Permissible(const Creature* creature)
{
    if (creature->IsPet())
        return PERMIT_BASE_SPECIAL;

    return PERMIT_BASE_NO;
}

PetAI::PetAI(Creature* c) : CreatureAI(c), i_tracker(TIME_INTERVAL_LOOK)
{
    m_AllySet.clear();
    UpdateAllies();
}

void PetAI::EnterEvadeMode()
{
}

bool PetAI::_needToStop() const
{
    // This is needed for charmed creatures, as once their target was reset other effects can trigger threat
    if (me->isCharmed() && me->GetVictim() == me->GetCharmer())
        return true;

    if (Unit* owner = me->GetCharmerOrOwner())
        if (owner->GetExactDist(me) >= (owner->GetVisibilityRange() - 10.0f))
            return true;

    if (me->GetExactDist(me->GetVictim()) > me->GetVisibilityRange() - 5.0f)
        return true;

    return !me->canAttack(me->GetVictim());
}

void PetAI::_doMeleeAttack()
{

    if (!_canMeleeAttack())
        return;

    DoMeleeAttackIfReady();
}

bool PetAI::_canMeleeAttack() const
{
    return me->GetEntry() != 416 /*ENTRY_IMP*/ &&
        me->GetEntry() != 510; /*ENTRY_WATER_ELEMENTAL*/
}

void PetAI::_stopAttack()
{
    if (!me->IsAlive())
    {
        DEBUG_LOG("Creature stoped attacking because he is dead [guid=%u]", me->GetGUIDLow());
        me->GetMotionMaster()->Clear();
        me->GetMotionMaster()->MoveIdle();
        me->CombatStop();
        me->getHostileRefManager().deleteReferences();

        return;
    }

    me->AttackStop();
    me->InterruptNonMeleeSpells(false);
    me->SendMeleeAttackStop(); // Should stop pet's attack button from flashing
    me->GetCharmInfo()->SetIsCommandAttack(false);
    HandleReturnMovement();
}

void PetAI::UpdateAI(const uint32 diff)
{
    if (!me->IsAlive() || !me->GetCharmInfo())
        return;

    Unit* owner = me->GetCharmerOrOwner();

    if (m_updateAlliesTimer <= diff)
        // UpdateAllies self set update timer
        UpdateAllies();
    else
        m_updateAlliesTimer -= diff;

    if (me->GetVictim() && me->GetVictim()->IsAlive())
    {
        // is only necessary to stop casting, the pet must not exit combat
        if (!me->GetCurrentSpell(CURRENT_CHANNELED_SPELL) && // ignore channeled spells (Pin, Seduction)
            me->GetVictim()->HasBreakableByDamageCrowdControlAura(me))
        {
            me->InterruptNonMeleeSpells(false);
            if (Unit* nextTarget = SelectNextTarget())
                AttackStart(nextTarget);
            return;
        }

        if (_needToStop())
        {
            DEBUG_LOG("Pet AI stoped attacking [guid=%u]", me->GetGUIDLow());
            _stopAttack();
            return;
        }

        // Check before attacking to prevent pets from leaving stay position
        if (me->GetCharmInfo()->HasCommandState(COMMAND_STAY))
        {
            if (me->GetCharmInfo()->IsCommandAttack() || (me->GetCharmInfo()->IsAtStay() && me->IsWithinMeleeRange(me->GetVictim())))
                _doMeleeAttack();
        }
        else
            _doMeleeAttack();
    }
    else
    {
        if (owner && owner->IsInCombat() && (me->HasReactState(REACT_AGGRESSIVE) || me->GetCharmInfo()->IsAtStay()))
        {
            // Every update we need to check targets only in certain cases
            // Aggressive - Allow auto select if owner or pet don't have a target
            // Stay - Only pick from pet or owner targets / attackers so targets won't run by
            //   while chasing our owner. Don't do auto select.
            // All other cases (ie: defensive) - Targets are assigned by DamageTaken(), OwnerAttackedBy(), OwnerAttacked(), etc.
            if (Unit* nextTarget = SelectNextTarget())
                AttackStart(nextTarget);
            else
                HandleReturnMovement();
        }
        else
            HandleReturnMovement();
    }

    // Autocast (cast only in combat or persistent spells in any state)
    if (!me->HasUnitState(UNIT_STATE_CASTING) && me->GetGlobalCooldown() == 0)
    {
        typedef std::vector<std::pair<Unit*, Spell*> > TargetSpellList;
        TargetSpellList  targetSpellStore;

        for (uint8 i = 0; i < me->GetPetAutoSpellSize(); ++i)
        {
            uint32 spellID = me->GetPetAutoSpellOnPos(i);
            if (!spellID)
                continue;

            SpellEntry const* spellInfo = sSpellStore.LookupEntry(spellID);
            if (!spellInfo)
                continue;

            if (!me->GetVictim())
            {
                // ignore attacking spells, and allow only self/around spells
                if (!IsPositiveSpell(spellInfo->Id))
                    continue;

                if (!IsNonCombatSpell(spellInfo))
                {
                    // Check if we're in combat or commanded to attack
                    if (!me->IsInCombat() && !me->GetCharmInfo()->IsCommandAttack())
                        continue;
                }

                Spell* spell = new Spell(me, spellInfo, 0);
                bool spellUsed = false;

                // Some spells can target enemy or friendly (DK Ghoul's Leap)
                // Check for enemy first (pet then owner)
                Unit* target = me->getAttackerForHelper();
                if (!target && owner)
                    target = owner->getAttackerForHelper();

                if (target)
                {
                    if (_CanAttack(target) && spell->CanAutoCast(target))
                    {
                        targetSpellStore.push_back(std::make_pair(target, spell));
                        spellUsed = true;
                    }
                }

                // No enemy, check friendly
                if (!spellUsed)
                {
                    for (std::set<uint64>::const_iterator tar = m_AllySet.begin(); tar != m_AllySet.end(); ++tar)
                    {
                        Unit* ally = ObjectAccessor::GetUnit(*me, *tar);

                        //only buff targets that are in combat, unless the spell can only be cast while out of combat
                        if (!ally)
                            continue;

                        if (spell->CanAutoCast(ally))
                        {
                            targetSpellStore.push_back(std::make_pair(ally, spell));
                            spellUsed = true;
                            break;
                        }
                    }
                }

                // No valid targets at all
                if (!spellUsed)
                    delete spell;
            }
            else if (me->GetVictim() && _CanAttack(me->GetVictim()))
            {
                Spell* spell = new Spell(me, spellInfo, 0);
                if (spell->CanAutoCast(me->GetVictim()))
                    targetSpellStore.push_back(std::make_pair(me->GetVictim(), spell));
                else
                    delete spell;
            }
        }

        // found units to cast on to
        if (!targetSpellStore.empty())
        {
            TargetSpellList::iterator it = targetSpellStore.begin();
            std::advance(it, urand(0, targetSpellStore.size() - 1));

            Spell* spell = (*it).second;
            Unit*  target = (*it).first;

            targetSpellStore.erase(it);

            SpellCastTargets targets;
            targets.setUnitTarget(target);

            if (!me->HasInArc(float(M_PI), target))
            {
                me->SetInFront(target);
                if (target->GetTypeId() == TYPEID_PLAYER)
                    me->SendUpdateToPlayer(target->ToPlayer());

                if (owner && owner->GetTypeId() == TYPEID_PLAYER)
                    me->SendUpdateToPlayer(owner->ToPlayer());
            }

            me->AddCreatureSpellCooldown(spell->m_spellInfo->Id);
            if (me->IsPet())
                ((Pet*)me)->CheckLearning(spell->m_spellInfo->Id);


            spell->prepare(&targets);
        }

        // deleted cached Spell objects
        for (TargetSpellList::const_iterator itr = targetSpellStore.begin(); itr != targetSpellStore.end(); ++itr)
            delete itr->second;
    }

    // Update speed as needed to prevent dropping too far behind and despawning
}


void PetAI::UpdateAllies()
{
    m_updateAlliesTimer = 10 * IN_MILLISECONDS;              //update friendly targets every 10 seconds, lesser checks increase performance

    Unit* owner = me->GetCharmerOrOwner();
    if (!owner)
        return;

    Group* group = NULL;
    if (Player* player = owner->ToPlayer())
        group = player->GetGroup();

    //only pet and owner/not in group->ok
    if (m_AllySet.size() == 2 && !group)
        return;

    //owner is in group; group members filled in already (no raid -> subgroupcount = whole count)
    if (group && !group->isRaidGroup() && m_AllySet.size() == (group->GetMembersCount() + 2))
        return;

    m_AllySet.clear();
    m_AllySet.insert(me->GetGUID());
    if (group)                                              //add group
    {
        for (GroupReference* itr = group->GetFirstMember(); itr != NULL; itr = itr->next())
        {
            Player* Target = itr->GetSource();
            if (!Target || !group->SameSubGroup(owner->ToPlayer(), Target))
                continue;

            if (Target->GetGUID() == owner->GetGUID())
                continue;

            m_AllySet.insert(Target->GetGUID());
        }
    }
    else                                                    //remove group
        m_AllySet.insert(owner->GetGUID());
}

void PetAI::KilledUnit(Unit* victim)
{
    // Called from Unit::Kill() in case where pet or owner kills something
    // if owner killed this victim, pet may still be attacking something else
    if (me == victim || (me->GetVictim() && me->GetVictim() != victim))
        return;

    // Clear target just in case. May help problem where health / focus / mana
    // regen gets stuck. Also resets attack command.
    // Can't use _stopAttack() because that activates movement handlers and ignores
    // next target selection
    me->AttackStop();
    me->InterruptNonMeleeSpells(false);
    me->SendMeleeAttackStop();  // Stops the pet's 'Attack' button from flashing

    // Before returning to owner, see if there are more things to attack
    if (Unit* nextTarget = SelectNextTarget())
        AttackStart(nextTarget);
    else
    {
        if (!me->GetCharmInfo())
            return;

        // Cancels the attack command so the pet stops chasing the
        // target it is attacking, and returns the pet to his owner
        me->GetCharmInfo()->SetIsCommandAttack(false);
        HandleReturnMovement();
    }
}

void PetAI::AttackStart(Unit* target)
{
    // Overrides Unit::AttackStart to correctly evaluate Pet states

    // Check all pet states to decide if we can attack this target
    if (!me->GetCharmInfo() || !_CanAttack(target))
        return;

    // Only chase if not commanded to stay or if stay but commanded to attack
    DoAttack(target, (!me->GetCharmInfo()->HasCommandState(COMMAND_STAY) || me->GetCharmInfo()->IsCommandAttack()));
}

void PetAI::OwnerAttackedBy(Unit* attacker)
{
    if (!attacker)
        return;

    if (me->HasReactState(REACT_PASSIVE))
        return;

    if (me->GetVictim() && me->GetVictim()->IsAlive())
        return;

    AttackStart(attacker);
}

void PetAI::OwnerAttacked(Unit* target)
{
    // Called when owner attacks something. Allows defensive pets to know
    //  that they need to assist

    // Target might be NULL if called from spell with invalid cast targets
    if (!target)
        return;

    // Passive pets don't do anything
    if (me->HasReactState(REACT_PASSIVE))
        return;

    // Prevent pet from disengaging from current target
    if (me->GetVictim() && me->GetVictim()->IsAlive())
        return;

    // Continue to evaluate and attack if necessary
    AttackStart(target);
}

Unit* PetAI::SelectNextTarget()
{
    Unit* owner = me->GetCharmerOrOwner();
    // Provides next target selection after current target death

    // Passive pets don't do next target selection
    if (me->HasReactState(REACT_PASSIVE))
        return NULL;

    if (Unit* ownerAttacker = owner->getAttackerForHelper())
        if (!ownerAttacker->HasBreakableByDamageCrowdControlAura() && me->CanCreatureAttack(ownerAttacker))
            return ownerAttacker;

    if (Unit* myAttacker = me->getAttackerForHelper())
        if (!myAttacker->HasBreakableByDamageCrowdControlAura(me) && me->CanCreatureAttack(myAttacker))
            return myAttacker;

    // Check pet attackers first so we don't drag a bunch of targets to the owner
    if (Unit* myAttacker = me->getAttackerForHelper())
        return myAttacker;

    // Not sure why we wouldn't have an owner but just in case...
    if (!me->GetCharmerOrOwner())
        return NULL;

    // Check owner attackers
    if (Unit* ownerAttacker = me->GetCharmerOrOwner()->getAttackerForHelper())
        return ownerAttacker;

    // Default - no valid targets
    return NULL;
}

void PetAI::HandleReturnMovement()
{
    // Handles moving the pet back to stay or owner

    // Prevent activating movement when under control of spells
    // such as "Eyes of the Beast"
    if (me->isCharmed())
        return;

    if (me->GetCharmInfo()->HasCommandState(COMMAND_STAY))
    {
        if (!me->GetCharmInfo()->IsAtStay() && !me->GetCharmInfo()->IsReturning())
        {
            float x, y, z;

            me->GetCharmInfo()->GetStayPosition(x, y, z);
            ClearCharmInfoFlags();
            me->GetCharmInfo()->SetIsReturning(true);
            me->GetMotionMaster()->Clear();
            me->GetMotionMaster()->MovePoint(me->GetGUIDLow(), x, y, z);
        }
    }
    else // COMMAND_FOLLOW
    {
        if (!me->GetCharmInfo()->IsFollowing() && !me->GetCharmInfo()->IsReturning())
        {
            ClearCharmInfoFlags();
            me->GetCharmInfo()->SetIsReturning(true);
            me->GetMotionMaster()->Clear();
            me->GetMotionMaster()->MoveFollow(me->GetCharmerOrOwner(), PET_FOLLOW_DIST, me->GetFollowAngle());
        }
    }

    me->DeleteThreatList();
    me->ClearInPetCombat();
}

void PetAI::DoAttack(Unit* target, bool chase)
{
    // Handles attack with or without chase and also resets flags
    // for next update / creature kill

    if (chase)
    {
        if (me->Attack(target, true))
        {
            bool oldCmdAttack = me->GetCharmInfo()->IsCommandAttack(); // This needs to be reset after other flags are cleared
            ClearCharmInfoFlags();
            me->GetCharmInfo()->SetIsCommandAttack(oldCmdAttack); // For passive pets commanded to attack so they will use spells
            me->GetMotionMaster()->Clear();
            me->GetMotionMaster()->MoveChase(target);
        }
    }
    else // (Stay && ((Aggressive || Defensive) && In Melee Range)))
    {
        ClearCharmInfoFlags();
        me->GetCharmInfo()->SetIsAtStay(true);
        me->GetMotionMaster()->Clear();
        me->GetMotionMaster()->MoveIdle();
    }
}

/// Receives notification when pet reaches stay or follow owner
void PetAI::MovementInform(uint32 moveType, uint32 data)
{
    if (!me->GetCharmInfo())
        return;

    switch (moveType)
    {
    case POINT_MOTION_TYPE:
    {
        // Pet is returning to where stay was clicked. data should be
        // pet's GUIDLow since we set that as the waypoint ID
        if (data == me->GetGUIDLow() && me->GetCharmInfo()->IsReturning())
        {
            ClearCharmInfoFlags();
            me->GetCharmInfo()->SetIsAtStay(true);
            me->GetMotionMaster()->Clear();
            me->GetMotionMaster()->MoveIdle();
        }
        break;
    }
    case FOLLOW_MOTION_TYPE:
    {
        // If data is owner's GUIDLow then we've reached follow point
        if (me->GetCharmerOrOwner() && data == me->GetCharmerOrOwner()->GetGUIDLow() && me->GetCharmInfo()->IsReturning())
        {
            ClearCharmInfoFlags();
            me->GetCharmInfo()->SetIsFollowing(true);
            me->AddUnitState(UNIT_STATE_FOLLOW);
        }
        break;
    }
    default:
        break;
    }
}

bool PetAI::_CanAttack(Unit* target)
{

    // Evaluates wether a pet can attack a specific target based on CommandState, ReactState and other flags

    if (!target)
        return false;

    if (!target->IsAlive())
    {
        // Clear target to prevent getting stuck on dead targets
        me->AttackStop();
        me->InterruptNonMeleeSpells(false);
        me->SendMeleeAttackStop();
        return false;
    }

    // Passive - passive pets can attack if told to
    if (me->HasReactState(REACT_PASSIVE))
        return me->GetCharmInfo()->IsCommandAttack();

    // Returning - pets ignore attacks only if owner clicked follow
    if (me->GetCharmInfo()->IsReturning())
        return false;

    // Is owner on a mount
    if (me->IsPet() && me->ToPet()->GetModeFlags() & PET_MODE_DISABLE_ACTIONS)
        return false;

    if (target->HasBreakableByDamageCrowdControlAura())
        return me->GetCharmInfo()->IsCommandAttack();

    // Stay - can attack if target is within range or commanded to
    if (me->GetCharmInfo()->HasCommandState(COMMAND_STAY))
        return (me->IsWithinMeleeRange(target, MELEE_RANGE) || me->GetCharmInfo()->IsCommandAttack());

    //  Pets attacking something (or chasing) should only switch targets if owner tells them to
    if (me->GetVictim() && me->GetVictim() != target)
    {
        // Check if our owner selected this target and clicked "attack"
        Unit* ownerTarget = NULL;
        if (Player* owner = me->GetCharmerOrOwner()->ToPlayer())
            ownerTarget = owner->GetSelectedUnit();
        else
            ownerTarget = me->GetCharmerOrOwner()->GetVictim();

        if (ownerTarget && me->GetCharmInfo()->IsCommandAttack())
            return (target->GetGUID() == ownerTarget->GetGUID());
    }

    // Follow
    if (me->GetCharmInfo()->HasCommandState(COMMAND_FOLLOW))
        return true;

    // default, though we shouldn't ever get here
    return false;
}

void PetAI::ClearCharmInfoFlags()
{
    // Quick access to set all flags to FALSE

    CharmInfo* ci = me->GetCharmInfo();

    if (ci)
    {
        ci->SetIsAtStay(false);
        ci->SetIsCommandAttack(false);
        ci->SetIsFollowing(false);
        ci->SetIsReturning(false);
    }
}

void PetAI::AttackedBy(Unit* attacker)
{
    // Called when pet takes damage. This function helps keep pets from running off
    //  simply due to gaining aggro.

    if (!attacker)
        return;

    // Passive pets don't do anything
    if (me->HasReactState(REACT_PASSIVE))
        return;

    // Prevent pet from disengaging from current target
    if (me->GetVictim() && me->GetVictim()->IsAlive())
        return;

    // Continue to evaluate and attack if necessary
    AttackStart(attacker);
}